1. Field of the Invention
The present invention relates to an information recording apparatus, an information recording method and an integrated circuit for recording information on an information recording medium such as an optical disc.
2. Description of the Background Art
Optical discs such as BDs (Blu-Ray Discs), DVDs (Digital Versatile Discs) and CDs (Compact Discs) are known information recording media.
A recording method called a write and verify processing is known as a recording method for such optical discs. The write and verify processing is a data recording method for recording data (information) while ensuring the reliability thereof by reproducing the data after the recording thereof and checking (verifying) whether or not the data can be correctly reproduced.
A conventional write and verify processing is described below with reference to drawings.
FIG. 14 is a diagram showing the construction of a conventional information recording apparatus 101. In FIG. 14, the information recording apparatus 101 is provided with a disc motor 112, an optical pickup 113, a servo controller 114, a buffer memory 115, a host interface 116, a recording/reproducing unit 118, and a drive controller 122. The recording/reproducing unit 118 includes a modem 119, an error correction coder 120 and a recording/reproduction controller 121.
The disc motor 112 rotates an optical disc 111. The optical pickup 113 irradiates the optical disc 111 with a laser beam to reproduce and record data from and on the optical disc 111. The servo controller 114 controls the disc motor 112 and the optical pickup 113 to optimally control a number of revolutions, focusing and tracking.
The drive controller 122 controls the overall operation of the information recording apparatus 101. The drive controller 122 performs an error processing according to a generated error. The recording/reproducing unit 118 performs a data processing for recoding or reproduction. The recording/reproducing unit 118 includes the modem 119, the error correction coder 120 and the recording/reproduction controller 121, wherein the recording/reproduction controller 121 controls the modem 119 and the error correction coder 120. The recording/reproducing unit 118 also returns a result of a record or reproduction (verify) processing instructed from the drive controller 122 as a status to the drive controller 122.
The modem 119 decodes reproduced data obtained from the optical pickup 113 to generate decoded data at the time of data reproduction. The modem 119 modulates coded data obtained from the error correction coder 120 to generate recording data at the time of data recoding. However, the modem 119 cannot simultaneously modulate and demodulate.
The error correction coder 120 performs an error correction to the decoded data obtained from the modem 119 and stores it in the buffer memory 115 at the time of data reproduction. The error correction coder 120 codes the data stored in the buffer memory 115 to generate coded data. However, the error correction coder 120 cannot simultaneously perform an error correction and coding.
The buffer memory 115 stores reproduced data and data to be recorded. The buffer memory 115 transmits and receives data to and from a host 117 via the host interface 116.
FIG. 15 is a flow chart showing the conventional write and verify processing performed to a rewritable optical disc.
First of all, in Step S101, the drive controller 122 instructs the servo controller 114 to move the optical pickup 113 to a position before a data recording region to have data recorded therein. The servo controller 114 controls the optical pickup 113, causes the optical pickup 113 to move to the position before the data recording region and waits on standby (waits for rotation) until the optical pickup 113 reaches the data recording region.
Further, the drive controller 122 issues a record command to the recording/reproducing unit 118. Upon the issuance of the record command, the recording/reproduction controller 121 reads data to be recorded stored in the buffer memory 115 to the error correction coder 120. The error correction coder 120 codes the read data to generate coded data, and outputs it to the modem 119. The modem 119 modulates the coded data to generate recording data.
Subsequently, in Step S102, the recording/reproduction controller 121 controls the optical pickup 113 to irradiate the optical disc 111 with a laser beam, thereby recording the recording data on the optical disc 111 when the optical pickup 113 reaches the data recording region. The recording/reproduction controller 121 returns a recording result as a status to the drive controller 122.
Subsequently, in Step S103, the drive controller 122 discriminates based on the status transmitted from the recording/reproduction controller 121 whether or not any error has occurred during the execution of the record command. If an error is judged to have occurred (YES in Step S103), a processing of Step S104 follows. On the other hand, no error occurrence is judged (NO in Step S103), a processing of Step S105 follows.
Subsequently, in Step S104, the drive controller 122 controls the recording/reproducing unit 118 to perform a defect replacement processing for recording the data stored in the buffer memory 115 and to be recorded in a region where the error occurred in a spare region. The processing of Step S104 corresponds to a recording error processing.
Subsequently, in Step S105, the drive controller 122 instructs the servo controller 114 to move the optical pickup 113 to a position before a region to be verified. The servo controller 114 controls the optical pickup 113 to move the optical pickup 113 to the position before the region to be verified, and waits on standby (waits for rotation) until the optical pickup 113 reaches the region to be verified. Further, the drive controller 122 issues a verify command to the recording/reproducing unit 118.
Subsequently, in Step S106, the recording/reproduction controller 121 controls the optical pickup 113 to irradiate the optical disc 111 with a laser beam and reproduce the data from the optical disc 111 when the optical pickup 113 reaches the region to be verified. The modem 119 demodulates the reproduced data to generate demodulated data, and the error correction coder 120 performs an error correction to the demodulated data and stores it in the buffer memory 115. The recording/reproduction controller 121 returns a verification result as a status to the drive controller 122.
Subsequently, in Step S107, the drive controller 122 discriminates based on the status whether or not any error has occurred during the execution of the verify command. If an error is judged to have occurred (YES in Step S107), a processing of Step S108 follows. On the other hand, if no error occurrence is judged (NO in Step S107), a processing of Step S111 follows.
Subsequently, in Step S108, the drive controller 122 controls the recording/reproducing unit 118 to perform a power-up retry processing for performing a record processing and a verify processing again to the verification region where the error occurred with a recording power changed.
Subsequently, in Step S109, the drive controller 122 discriminates based on the status whether or not any error has occurred during the execution of the power-up retry processing. If an error is judged to have occurred (YES in Step S109), a processing of Step S110 follows. On the other hand, if no error occurrence is judged (NO in Step S109), the processing of Step S111 follows.
Subsequently, in Step S110, the drive controller 122 controls the recording/reproducing unit 118 to perform a defect replacement processing for recording the data stored in the buffer memory 115 and to be recorded in the region where the error occurred in a spare region. The processings of Steps S108 to S110 correspond to a verification error processing.
Subsequently, in Step S111, the drive controller 122 discriminates whether there is any region to be verified. If a region to be verified is judged to be present (YES in Step S111), the processing of Step S105 follows. On the other hand, if the absence of the region to be verified is judged (NO in Step S111), a processing of Step S112 follows.
Subsequently, in Step S112, the drive controller 122 discriminates whether or not there is any processing requiring region where the write and verify processing should be performed. If a processing requiring region is judged to be present (YES in Step S112), the processing of Step S101 follows. On the other hand, if the absence of the processing requiring region is judged (NO in Step S112), the write and verify processing is ended.
FIG. 16 is a chart showing an operation of the conventional information recording apparatus 101 in chronological order.
In FIG. 16, the optical disc 111 is composed of a plurality of clusters. Each cluster is a recording unit by which data is recorded on the optical disc 111. A BD is composed of 32 sectors, and a DVD is composed of 16 sectors. Here, it is assumed that the buffer memory 115 can store data of 5 clusters.
In the event of an error during the verification, the defect replacement processing for recording data in a spare region is performed in Step S110 of FIG. 15. Thus, data to be recorded has to be stored in the buffer memory 115 until the verification is completed. Therefore, a region where data can be recorded in one processing is limited to a storable data amount (5 clusters) of the buffer memory 115. In one processing of recording data of 10 clusters as in FIG. 16, the write and verify processing comprised of the record processing and the verify processing is performed twice. If it is assumed that a region to be verified is a verification region and a region to have data recorded therein is a recording region, there are a seeking motion 207 and a rotation waiting motion 208, which are redundant, between a first verification region 206 and a second recording region 209.
As described above, in the conventional write and verify processing, the redundant seeking and rotation waiting are present between verification and recording, whereby there was a problem of elongating a recording time. Influences caused by this problem become larger as data to be recorded increases, the capacity of the buffer memory decreases or multiple speed increases.
Accordingly, Japanese Unexamined Patent Publication No. H08-328752 discloses a method for successively performing verification and recording by eliminating redundant seeking and rotation waiting. However, the modem 119 cannot simultaneously perform modulation and demodulation and the error correction coder 120 cannot simultaneously perform error correction and coding. Further, a period from the end of the verification region to the leading end of the recording region is very short. Thus, it is difficult to instantaneously switch the modem 119 and the error correction coder 120 and generate modulated recording data until the leading end of the recording region is reached.
As shown in FIG. 17, the demodulation in the modem 119 is completed at an end 221 of the verification region, and an error correction can be performed by the error correction coder 120 to discriminate whether or not any error has occurred during the verification at a point of time 222 after the recording is started. In other words, if an error-correction error occurred during the verification in a region immediately before the recording region and the processing was interrupted, data is already recorded in the next region. Accordingly, in the case of application to a recordable optical disc such as a BD-R, there is a problem that data is not correctly recorded in a recording region next to a verification region where an error occurred during verification.
Accordingly, Publication of Japanese Patent No. 2800319 discloses a method for reducing the number of clusters to be verified and providing a specified region (gap region 307) between a verification region 306 and a recording region 308 as shown in FIG. 18 in order to ensure a time until preparation for the next recording is completed. According to this method, the recording/reproduction unit 118 can generate recording data until the optical pickup 113 reaches the leading end of the recording region 308 from the end of the verification region 306. Further, even if an error-correction error occurs in the verification region 306, the processing can be interrupted without recording data in the next recording region, wherefore application to a recordable optical disc such as a BD-R is possible.
In a write and verify processing of Publication of Japanese Patent No. 2800319, the record processing is started until a recording start position is reached after the verify processing is performed. However, a record processing starting control considering a timing to catch up with the start of recording is necessary in the conventional write and verify processing. Since a time required for the optical pickup 113 to pass the gap region changes according to a multiple speed or a radial position, it is difficult to control the start timing of the record processing.
Thus, there is a recording method for adding a function of performing a sequence of the verify processing, the gap region passage and the record processing at once and performing a series of processings upon one processing start. In the batch recording method for performing the processings at once, it is sufficient to perform a start processing similar to the conventional one at the start of verification and the above timing control is unnecessary. Therefore, the write and verify processing is preferably realized by this recording method.
However, since information only on an execution result can be obtained for one processing start in the batch recording method, it cannot be discriminated in which of the verification region, the gap region and the recording region an error occurred.
Since a characteristic of the cause of error differs depending on whether the region where the error occurred is the verification region or the recording region in the conventional information recording apparatus, an error processing suitable for each characteristic is performed.
A main cause of error occurring in the recording region is an initial defect which occurs in the optical disc manufacturing process, or a secondary defect such as scratches and fingerprint adhesion which occur upon using an optical disc and deterioration of the optical disc with time. A defect has a high possibility of recurring errors even if a retry such as rewriting is made since the region itself is defective. Thus, in the event of an error in the recording region, a defect replacement processing is performed to record information in a spare recording region (spare region) free from defects.
Since the verify processing is performed to the region where information could be normally recorded, a servo adjustment or a power adjustment of a laser beam becomes insufficient due to a characteristic variation of the optical disc or the optical pickup in addition to an error resulting from a medium defect, thereby deteriorating recording quality or reproduction quality. This makes it impossible to perform an error correction and causes a servo deviation, which causes an error occurring in the verification region. Such an error has a high possibility of being corrected by rewriting and reverifying with the laser beam power or servo adjusted. Thus, in the event of an error in the verification region, a power-up retry processing for rewriting with the recording power changed is performed. If an error occurs nevertheless, it is known to perform a defect replacement processing similar to the recording.
A main cause of error occurring in the gap region is late recording preparation such as switching of the modem and the error correction coder and generation of recording data for the start of the recording and a servo deviation due to an accidental impact on a drive. If the recording preparation is late for the start of the recording, a processing specific to the gap region for ensuring the gap region necessary for the recording preparation by extending the gap region has to be performed. Further, since the record processing and the verify processing are not performed in the gap region, it is not necessary to perform a defect replacement processing and a power-up retry processing for such an error.
However, it cannot be discriminated in which of the verification region, the gap region and the recording region an error occurred in the batch recording method. Thus, if the defect replacement processing as an error processing in the recording region is performed when an error occurred, it is performed also to the verification region that can be reproduced by rewriting and reverifying and the gap region that can be normally verified and requires no defect replacement processing. As a result, there is a possibility that a recording time increases, the spare region is used up and data cannot be recorded on the optical disc.
If the power-up retry processing and the defect replacement processing as error processings in the verification region are performed in the event of an error, they are performed also to the recording region that has a high possibility of errors even if the power-up retry processing is performed and the gap region that can be normally verified and requires no power-up retry processing and defect replacement processing. As a result, there is a possibility of increasing a recording time.
As described above, in the conventional information recording apparatus, it cannot be discriminated in which of the verification region, the gap region and the recording region an error occurred. Thus, if error processing(s) unstable for the region where the error occurred is/are performed, the unnecessary defect replacement processing and power-up retry processing are performed, which causes problems of increasing the recording time, using up the spare region and being unable to record data on the optical disc.
Since an error occurring when the recording preparation cannot be made in time results from the switching of the modem and the error correction coder, this is an error which occurs also in the verification region or the recording region. However, the gap region needs not be extended when an error occurs in the verification region or the recording region. Thus, if it cannot be discriminated in which region an error occurred, the gap region is always extended, which causes problems of increasing a gap region passing time and increasing the recording time.